damaged and up to 250,000 used cars. >> reporter: and guess where many, if not most, will end up? >> put back into the market and resold to unsuspecting consumers. >> reporter: so what do you do? >> the number one thing for anybody looking to buy a used car is to pull a vehicle history report. >> reporter: also, let a mechanic you trust take a look at it, or at the very least, inspect the car yourself and include a smell test. >> the odor. when a car sits in standing water, particularly in salt water, that car will take on a smell that's very difficult to get rid of. >> reporter: look for debris or water lines inside the car, the trunk, and engine compartment. dingy headlights and taillights could be a hint the car has been under water. plus, keep in mind there's nothing illegal about selling a once-flooded car, provided you know that before buying. >> if you get a really, really good deal on it, it might still be a good buy for you. >> reporter: but if you have doubts, don't get soaked.